1. Field of Invention
The present invention relates power converters, and more particularly, to delivering optimal charge bursts in a voltage regulator.
2. Description of Related Art
Power converters are essential for many modern electronic devices. Among other capabilities, power converters can adjust voltage level downward (buck converter) or adjust voltage level upward (boost converter). Power converters may also convert from alternating current (AC) power to direct current (DC) power, or vice versa. Power converters are typically implemented using one or more switching devices, such as transistors, which are turned on and off to deliver power to the output of the converter. Control circuitry is provided to regulate the turning on and off of the switching devices, and thus, these converters are known as “switching regulators” or “switching converters.” Such a power converter may be incorporated into or used to implement a power supply—i.e., a switching mode power supply (SMPS). The power converters may also include one or more capacitors or inductors for alternately storing and outputting energy.
Some switching converters may use higher frequency for switching on and off the switching devices, which makes the current ripple in the inductor smaller. This allows the switching converter to be implemented with smaller filter components, including the output capacitor. But when a smaller capacitor is used, it must be refreshed more frequently, thus sacrificing efficiency in the switching converter.
One conventional technique to charge the output filter capacitor by a given voltage delta employs multiple, small charge bursts. This results in lower regulator efficiency because it increases dynamic power train losses—i.e., the switching devices in the regulator must each be turned on N times (instead of just once) to achieve a given voltage delta.
Another conventional technique to charge the output filter capacitor in a switching regulator employs a single charge burst. With this technique, however, the voltage delta at the end of the single charge burst varies. The variable voltage delta degrades regulator efficiency because power train dynamic losses are increased—i.e., the frequency of the charge bursts is higher than necessary as regulator parameters are varied.